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authorMika Kahola <mika.kahola@intel.com>2020-05-06 14:08:27 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2020-05-08 12:12:58 +0200
commit50b6f619a099af6dfe06e958bfa08d46440ea788 (patch)
treebe819d1972f4b4a3aca810cb8ec33d6e64e20f41 /include/uapi/drm
parentdrm/ast: Don't check new mode if CRTC is being disabled (diff)
downloadlinux-50b6f619a099af6dfe06e958bfa08d46440ea788.tar.xz
linux-50b6f619a099af6dfe06e958bfa08d46440ea788.zip
uapi/drm/drm_fourcc.h: Note on platform specificity for format modifiers
Make an additional note on DRM format modifiers for x and y tiling. These format modifiers are defined for BDW+ platforms and therefore definition is not valid for older gens. This is due to address swizzling for tiled surfaces is no longer used. For newer platforms main memory controller has a more effective address swizzling algorithm. v2: Rephrase comment (Daniel) Signed-off-by: Mika Kahola <mika.kahola@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20200506120827.12250-1-mika.kahola@intel.com
Diffstat (limited to 'include/uapi/drm')
-rw-r--r--include/uapi/drm/drm_fourcc.h18
1 files changed, 12 insertions, 6 deletions
diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index 8bc0b31597d8..9e488d10f8b4 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -354,9 +354,12 @@ extern "C" {
* a platform-dependent stride. On top of that the memory can apply
* platform-depending swizzling of some higher address bits into bit6.
*
- * This format is highly platforms specific and not useful for cross-driver
- * sharing. It exists since on a given platform it does uniquely identify the
- * layout in a simple way for i915-specific userspace.
+ * Note that this layout is only accurate on intel gen 8+ or valleyview chipsets.
+ * On earlier platforms the is highly platforms specific and not useful for
+ * cross-driver sharing. It exists since on a given platform it does uniquely
+ * identify the layout in a simple way for i915-specific userspace, which
+ * facilitated conversion of userspace to modifiers. Additionally the exact
+ * format on some really old platforms is not known.
*/
#define I915_FORMAT_MOD_X_TILED fourcc_mod_code(INTEL, 1)
@@ -369,9 +372,12 @@ extern "C" {
* memory can apply platform-depending swizzling of some higher address bits
* into bit6.
*
- * This format is highly platforms specific and not useful for cross-driver
- * sharing. It exists since on a given platform it does uniquely identify the
- * layout in a simple way for i915-specific userspace.
+ * Note that this layout is only accurate on intel gen 8+ or valleyview chipsets.
+ * On earlier platforms the is highly platforms specific and not useful for
+ * cross-driver sharing. It exists since on a given platform it does uniquely
+ * identify the layout in a simple way for i915-specific userspace, which
+ * facilitated conversion of userspace to modifiers. Additionally the exact
+ * format on some really old platforms is not known.
*/
#define I915_FORMAT_MOD_Y_TILED fourcc_mod_code(INTEL, 2)